HADOOP-18654. Remove unused custom appender TaskLogAppender

hadoop-common-project/hadoop-common/src/main/conf/log4j.properties

@@ -75,14 +75,6 @@ log4j.appender.console.target=System.err
 log4j.appender.console.layout=org.apache.log4j.PatternLayout
 log4j.appender.console.layout.ConversionPattern=%d{ISO8601} %p %c{2}: %m%n
 
-#
-# TaskLog Appender
-#
-log4j.appender.TLA=org.apache.hadoop.mapred.TaskLogAppender
-
-log4j.appender.TLA.layout=org.apache.log4j.PatternLayout
-log4j.appender.TLA.layout.ConversionPattern=%d{ISO8601} %p %c: %m%n
-
 #
 # HDFS block state change log from block manager
 #

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/TaskLog.java

@@ -256,17 +256,6 @@ public synchronized static void syncLogs(String logLocation,
   throws IOException {
     System.out.flush();
     System.err.flush();
-    Enumeration<Logger> allLoggers = LogManager.getCurrentLoggers();
-    while (allLoggers.hasMoreElements()) {
-      Logger l = allLoggers.nextElement();
-      Enumeration<Appender> allAppenders = l.getAllAppenders();
-      while (allAppenders.hasMoreElements()) {
-        Appender a = allAppenders.nextElement();
-        if (a instanceof TaskLogAppender) {
-          ((TaskLogAppender)a).flush();
-        }
-      }
-    }
     if (currentTaskid != taskid) {
       currentTaskid = taskid;
       resetPrevLengths(logLocation);